OrionOpticsUK AG8 astrograph

Quick Overview

The AG8 is the most compact model in astrograph range of OrionOpticsUK. With an aperture of 200mm and a great f3.8 focal ratio, you can use it also with compact mounts and you will be able to record great deep-sky images also with relatively short exposition times. Thanks to the carbon fibre tube and the high quality mechanics, the AG8 telescope is really lightweight but also very stable: this means you won't have big problems with temperature variations and collimation. Together with high quality OrionOpticsUK optics, that's the key for its and your success.

Details

AG telescopes are precision computer designed, hand built instruments. The flat fields are achieved by employing a state of the art, lens corrector system, designed especially to produce a wide, flat fields up to 60mm diameter. All AG telescopes are supplied as standard with ACU-3 custom designed and built 3" focusers (76.2mm) to offer excellent stability over a wide range of camera loads. To aid stability even further, OrionOpticsUK also offer FocusForm equipment to reinforce every possible position where the smallest amount of flexure could take place, ensuring a rock steady platform for perfect, reliable, repeatable focusing of the image on your camera chip. Air cooling fans are fitted as standard in the telescope's main mirror cell to introduce cooling air to reach ambient temperature quickly and evenly assuring you of steady air within the tube and little or no possible currents to detract from a perfect image.

All AG primary mirrors are made from Schott Borosilicate Low Expansion Suprax glass (virtually identical to Pyrex) and OrionOpticsUK doesn’t release one to its coating department unless it achieves a surface accuracy of 1/16 wave or better. They test every optics with one of the worlds most exacting measuring devices, a Zygo Laser Interferometer that can measure optical distances which are smaller than 2,000 times the thickness of a human hair. The elliptical secondary mirrors are also made and Zygo tested to the highest standard, again in most instances (the larger sizes) OrionOpticsUK uses Suprax to give stability and accuracy. These, along with the primary mirrors are Hilux coated for the highest possible aluminium protected reflective surfaces available.

In order to produce the best astrophotography, telescopes need not only the best optics but also the best mechanics and materials. OrionOpticsUK uses extremely high grade of carbon and resin is to achieve a virtual zero expansion rate and incredible strength (the same materials as ones used on both Formula 1 racing cars, aerospace technology and orbiting Earth satellites): this way AG telescopes will maintaining a precise focal plane position and, an extremely rigid, and non flexible tube. ;It is relatively easy to produce significantly lesser quality tubes and the lower price of the telescope is a feature of this. However, this can be a false economy if you are after producing the finest images possible. If you have a tube which flexes slightly or has a lower grade carbon/resin construction, there is virtually nothing you can do about it, you have got what you paid for and must live with it.

AG telescopes comes with the X0.95 Wynne corrector inside of the telescope's focuser. The corrector comprises of 4 elements of special glass types, two single lenses and a cemented doublet which enable the light from the telescope to be brought to a very wide, flat, false colour free focal plane of up to 60mm diameter field. The key to the design is the choice of some rare earth glass types and computer enhanced designing of the curves of the lenses. There are 4 lenses in our corrector, one more than competitors use for a specific reason. We have found that 3 lenses, which are commonly used in many systems, can produce good image qualities but, to get the best out of very accurate mirrors, you have to incorporate a fourth lens which enhances even further the optical performance.

AG telescopes come with ACU-3L focuser that has a full length draw tube 3” diameter, (76.2mm) internally threaded to accept the 3” Wynne corrector and other accessories. These are not just pushed in, they are screwed in by precision threads. This gives an incredible amount of strength and freedom from any flexure, so common in large, push fit focusers. The initial focusing is carried out by the silky smooth main focusing knobs and then, when perfect positioning is required, the slow motion knob with added internal weights takes over to give very, very smooth movement down at a reduced ratio speed of a factor of 10:1, it just glides along at a very smooth, slow and precise pace, you have to actually feel this to appreciate just how good it really is. Coupled with this smoothness comes strength. The ACU-3L carries most cameras on the market with ease, it really is a design which lends, smoothness, attractiveness and power which ensures you have no problems at all with this focuser.

This comparison table lists all the specifications of the AG telescopes, available in different diameters, from 200mm (8") to 400mm (16"). All of them have the same f3.8 focal ratio. In the image below, M42 image by Peter Shah recorded with AG8 telescope and SXV-H16 CCD camera.